Well, what did I learn from the week before when I made my little mushroom door for my fairy garden?
Pre-poke all your holes while the clay is still damp and then remove the objects before baking. After they have dried and cooled off you can re-reinsert pieces back into the clay with a touch of glue and you won't have to worry about anything cracking.
Reinforce heavy parts with a sturdy wire to make sure pieces don't fall over if they are not balanced like the top of the mushroom cap; which by the way, as thick as this piece was I had no cracking what so ever in it when it was dry.
If you want to have a curve to something you can use all sorts of items to set the curvature, just make sure to let the piece air dry and then remove said items before baking.
You might notice that all my pieces are on the baking tray, that's because I go ahead and move them over to the tray when I am adding the finishing touches so I have less of a chance damaging anything when they are ready to be baked.